Impeller seal for a centrifugal pump



in. 11, 1966 o. v. PAGE 3,228,342

IMPELLER SEAL FOR A CENTRIFUGAL PUMP Filed Nov. 13, 1963 2 Sheets-Sheet 1 jlgi INVENTOR OJWHLD V 1 /1 65 Jan. 11, 1966 o. v. PAGE IMPELLER SEAL FOR A GENTRIFUGAL PUMP 2 Sheets-Sheet 2 Filed Nov. 13, 1963 INVENTOR. Oswma V 37615 United States Patent IMPELLER SEAL FOR A CENTRIFUGAL PUMP Oswald V. Page, Mansfield, Ohio, assignor to Barnes gianufacturing Co., Mansfield, Ohio, a corporation of Filed Nov. 13, 1963, Ser- No. 323,294 7 Claims. (Cl. 103-111) The present invention relates to a centrifugal pump, and more particularly to a novel sealing means especially adapted for use between the rotatable impeller for said pump and the stationary part of the pump housing defining the inlet of the impeller chamber whereby the impeller may be rotatably actuated without any initial frictional drag being presented thereto by the sealing means at the instant of starting, said sealing means being thereafter responsive to the pump output fluid flow to effect a variable liquid seal between said impeller and said chamber inlet whereby all of the fluid flow into said inlet is directed into the eye of the impeller, and further whereby the impeller fluid output is prevented from flowing back through said inlet.

The centrifugal pump assembly of the present invention is especially adapted for utility with, though not limited to light duty pumps such as a pump used with domestic dishwashers and the like wherein it is necessary to have minimum frictional drag on the impeller at the instant of starting the pump so that the impeller inertia is readily overcome and the pump is hence brought up to full speed as quickly as possible.

It is therefore a primary object of the present invention to provide an improved sealing means especially designed for use in a centrifugal pump and which is adapted to be operably associated with the rotatable pump impeller and the adjacent stationary housing defining the inlet to the impeller chamber to provide a variable fluid seal therebetween such that at the instant of rotatably actuating the impeller the sealing means does not present any frictional drag thereto.

Another object of the present invention is to provide an improved sealing means especially designed for use in a centrifugal pump, being operably associated with the pump impeller and the adjacent stationary housing part defining the impeller chamber inlet, and which sealing means is responsive to the pump output flow.

Still another object of the present invention is to provide a novel sealing means for use in a centrifugal pump as above referred to and wherein the impeller has a central hollow hub that forms the inlet or eye therefor and which communicates with the inlet to the impeller chamber, the sealing means being operably associated with said hub and chamber inlet in such manner that the impeller may be rotatably actuated without any frictional drag being initially presented thereto by said sealing means, said sealing means being thereafter operable in response to the pump output flow to effect a variable fluid seal between said impeller hub and chamber inlet.

It is a further object to provide novel sealing means for the central hub portion of an impeller in a centrifugal pump, the sealing means including a cylindrical ring member formed of spirally or helically wound metallic wire which, by its configuration is substantially self lubricating, and a polyurethane U-shaped cup seal carried on the pump housing which is flexed into sealing engagement with said ring member when the impeller reaches a predetermined rotatable speed.

It is a further object of the present invention to provide novel sealing means for a central hub portion of an impeller of a centrifugal pump, the sealing means including a polytetrafluoroethylene wear ring on the hub portion that is flexible enough to take care of any slight irregularity in structural and/or rotational geometry of the impeller assembly.

It is also an object of the present invention to provide ice improved sealing means for the central inlet hub of an impeller for a centrifugal pump, the sealing means including a polytetrafluoroethylene wear ring on the impeller hub and a polyurethane U-shaped cup seal on its associated pump housing whereby the cup seal engages the wear ring when the impeller reaches a predetermined rotating speed to form an effective seal and, yet, the ring and cup seal are abrasion-resistant and long lasting.

Other objects will be apparent from the specification that follows, the appended claims and the drawings in which:

FIG. 1 is a fragmentary elevational view of a centrifugal pump embodying the novel sealing means of the present invention;

FIG. 2 is a fragmentary elevation of the impeller of the pump of FIG. 1 being drawn to an enlarged scale to more clearly illustrate the assembly;

FIG. 3 is a fragmentary elevation of the impeller of the pump of FIG. 1 but with a second embodiment of impeller seal being shown;

FIG. 4 is a fragmentary elevational view of a similar centrifugal pump showing a third embodiment of sealing means of the present invention; and,

FIG. 5 is a fragmentary elevation of the impeller of the pump of FIG. 4.

eferring now to FIGS. 1 and 2 of the drawings, a centrifugal pump 1 is herein shown comprising a housing 2 having an end hell 7 threadably mounted on transverse flange 8, said end bell defining an impeller chamber 5 provided with an outlet port 6. The flange 8 is formed with a central inlet port It). An impeller 15 is disposed in the chamber 5 being mounted on one end of a drive shaft 16 which partly extends into the chamber 5 through the inlet port 10 of said flange, said shaft extending downwardly therethrough and connecting with a suitable power source such as an electric motor (not shown). The impeller 15 comprises an upper shroud l8 and a lower shroud 19, the lower shroud having a central hub 20 that forms the impeller inlet opening or eye of the impeller assembly. The upper and lower shrouds are permanently attached to each other to form impeller passageways 21 communicating at one end with the impeller eye and at the opposite end with the chamber 5.

The hub 20 is formed with an annular groove 22 on its outer periphery and a wear ring member 25 con structed of rodlike material such as metallic stainless steel wire, helically or spirally wound into a cylinder, is disposed in said groove 22. As best seen in FIG. 2, round wire is preferably used.

An annular cup-shaped seal 30 formed of a rubbery material such as a polyurethane, is disposed in an annular recess 32 provided on the flange 8 adjacent the flange inlet 10.

The seal 30 includes an outer leg 34 that is preferably adhesively attached to wall 32:: defining one side of recess 32, the seal base leg 3% lying over wall 32b defining the adjacent side of recess 32.

In cross-sectional configuration, the seal 30 is seen to include a leg 35 which is integral with the opposite end of the base leg 30a, extending approximately perpendicularly outwardly therefrom so as to be positioned adjacent the wear ring member 25, being spaced in its normal non-flexed condition outwardly of said ring member a distance approximately one-tenth to one-third the thickness of leg 35.

The seal leg 35 is intended to be sufficiently flexible so as to be flexed inwardly and bear against the ring member 25 and thereby provide an effective fluid seal therebetween.

As is seen in FIG. 1, with the impeller stationary, the flexible leg 35 of the seal 30 is disposed in its static position i.c. spaced outwardly from the wear ring 25.

When the impeller is initially rotated, the flexible leg 35, being spaced from said wear ring, does not resist said impeller rotation, and hence the same is brought up to full speed within a substantially short period.

As the impeller is rotated it draws fluid into its central inlet or eye thus creating an inlet flow as depicted by arrows C.

Said inlet flow passes through the impeller passageways or vanes 21, being propelled outwardly nadial-ly therethrough into the chamber 5 whereat it defines the pump output D.

As the back or counter pressure within the chamber 5 increases consequent to said flow, the leg 35 of seal 30 is flexed inwardly whereby its lip 35a engages the outer surface of one or more convolutions of the wear ring 25 to thereby effect a fluid seal therebetween. -In this manner, a fluid seal is effected between the impeller chamber 5 and the chamber inlet thus preventing a backflow of fluid therebetween.

As will be apparent, the fluid pressure in the impeller chamber 5 increases in proportion to the increase in the speed of the impeller with a consequent increase in the force pressing the leg 35 of seal 30 against the wear ring thus resulting in a more eflective seal between said wear ring and seal leg.

It is intended that the fluid pressure in the chamber 5 will be of suflicient magnitude to initiate flexing of the eal leg 35 at approximately half the rated design speed of the impeller so that at low operating speeds therefor the seal leg 35 is spaced outwardly from the wear ring thereby not effecting or retarding its acceleration.

As aforementioned, round wire is preferably used for the ring member 25 whereby a continuous groove 41 is formed by the spiral convolutions of said member which groove progresses helically therearound.

With the ring member 25 mounted on the impeller, said groove 41, as best seen in FIG. 2, forms a channel into which a small quantity of fluid may flow which is eifective to Wet the wire, said fluid thus acting as a lubricant between the wire and leg 35 of the seal as said leg is flexed into engagement therewith being effective thereby to minimize wearing of said ring and eal.

The quantity of fluid lubricant is not intended to reduce the fluid pressure in the impeller chamber nor to decrease the effectiveness of the fluid seal between the ring member 25 and seal 30.

Another embodiment of impeller ring member is shown in FIG. 3, being identified by the reference numeral 45, and likewise preferably formed of tainless steel wire somewhat oval shaped in cross-sectional configuration and wound helically or spirally to form a cylinder.

This construction likewise provides a groove or channel 46 in said ring member formed by the convolutions of the spirally Wound wire material which functions to direct liquid between said convolutions effective to wet the outer surface thereof and hence lubricate the leg of the seal 30 as the latter sealingly engages said ring member.

In FIGS. 4 and 5 is shown a third embodiment of impeller ring member identified at 51, and which is cylindrical in form and constructed of polytetrafluoroethylene material.

In this assembly, the impeller hub 53 of impeller 54 is formed with an annular groove 56 into which the ring member is disposed.

The polytetrafluoroethylene material is preferably sufficiently plastic so as to tend to distort as the impeller is rotated. This characteristic of said material is utilized to drivingly connect said ring to the impeller by means of driving holes 61 formed in the hub and spaced circumferenti-ally therearound and into which the material defining the inner surface of said ring will move as the impeller is rotated. Thi deformation of the'ring material secures said ring Within the aforesaid groove and prevents it from slipping or riding out of the latter.

It will be further apparent that inasmuch a the wear ring 51 is constructed of highly abrasive resistant materials substantially little or no wear occurs between the same and the seal so that the pump operating life may be increased thereby.

Having thus described in detail, several preferred embodiments of sealing means especially designed for use in a centrifugal pump or the like it will be apparent that the same is susceptible to various modifications, changes and combinations of parts without departing from the inventive concepts thereof as are defined in the claims.

What is claimed is:

1. A centrifugal pump comprising a housing defining an impeller chamber, a driving shaft, an impeller rigidly connected to the shaft and adapted to rotate within said impeller chamber, aid impeller having a central hub that forms the inlet therefor, said hub mounting a cylindrical ring member thereon, a U-shaped annular cup seal of a rubbery material provided between said hub and said housing, said seal having one leg rigidly connected to the housing and a second leg located adjacent the hub, said econd leg being normally radially spaced from said ring member below a predetermined rotatable speed for said impeller and responsive to pressure in said chamher to flex and bear against said ring member when the impeller is rotating above said predetermined peed.

2. A pump as defined in claim 1 in which the second leg of the seal is normally spaced away from the hub below said predetermined impeller rotating speed a distance equal to about one-tenth to one-third the thickness of said leg.

3. A pump as defined in claim 1 and in which the ring member is formed of wirelike material helically wound to form a cylinder.

4. A pump as defined in claim 3 and wherein the helical convolutions form a spiral groove along said member which functions to lubricate the same.

5. A pump as defined in claim 1 in which said U- shaped cup seal is made of a polyurethane material.

6. A centrifugal pump comprising a housing defining an impeller chamber, a driving shaft, an impeller rigidly connected to the shaft and adapted to rotate within said impeller chamber, the impeller comprising an upper shroud and a lower shroud, said lower shroud having a central hub that form an inlet opening for said impeller, said hub having an annular groove around the outer periphery thereof and an annular flexible wear ring disposed in said groove, a U-shaped annular cup seal of a rubbery material provided between said hub and said housing, said seal having one leg rigidly connected .to the housing and a second leg located adjacent the hub, said second leg being normally radially spaced from said hub below a predetermined rotatable speed for said impeller and responsive to pressure in said chamber to flex and bear against said wear ring when the impeller i rotating above said predetermined speed.

7. A pump as defined in claim 6 and in which the wear ring is formed of polytetrafluoroethylene.

References Cited by the Examiner UNITED STATES PATENTS 2,021,346 11/1935 Allen 27781 X 2,257,507 9/1941 Mann 103-l 11 2,270,054 1/1942 Hogan 277- X 2,684,033 7/1954 Montgomery et al. l031ll 2,745,687 5/1956 Stock 1031 14 2,858,063 10/1958 Thylefors 103-111 3,037,458 6/1962 Olmstead et al 103-114 3,054,620 9/1962 Schwing 27795 X FOREIGN PATENTS 35,965 1/ 1909 Austria.

DONL'EY I. STOCKING, Primary Examiner.

HENRY F. RADUAZO, Examiner. 

1. A CENTRIFUGAL PUMP COMPRISING A HOUSING DEFINING AN IMPELLER CHAMBER, A DRIVING SHAFT, AN IMPELLER RIGIDLY CONNECTED TO THE SHAFT AND ADAPTED TO ROTATE WITHIN SAID IMPELLER CHAMBER, SAID IMPELLER HAVING A CENTRAL HUB THAT FORMS THE INLET THEREFOR, SAID HUB MOUNTING A CYLINDRICAL RING MEMBER THEREON, A U-SHAPED ANNULAR CUP SEAL OF A RUBBERY MATERIAL PROVIDED BETWEEN SAID HUB AND SAID HOUSING, SAID SEAL HAVING ONE LEG RIGIDLY CONNECTED TO THE HOUSING AND A SECOND LEG LOCATED ADJACENT THE HUB, SAID SECOND LEG BEING NORMALLY RADIALLY SPACED FROM SAID RING MEMBER BELOW A PREDETERMINED ROTATABLE SPEED FOR SAID IMPELLER AND RESPONSIVE TO PRESSURE IN SAID CHAMBER TO FLEX AND BEAR AGAINST SAID RING MEMBER WHEN THE IMPELLER IS ROTATING ABOVE SAID PREDETERMINED SPEED. 